Portable electronic device including tactile touch-sensitive input device and method of protecting same

ABSTRACT

A portable electronic device includes a housing with a base. A touch-sensitive input assembly is spaced from and moveable relative to the base and a stopping arrangement limits movement of the touch-sensitive input assembly in the direction of the base. An actuating arrangement including a piezoelectric actuator is disposed between the touch-sensitive input assembly and the base for selectively receiving an applied voltage to thereby apply a force to the touch-sensitive input assembly. An accelerometer and functional components are housed within the housing. The functional components include a memory and a processor operably connected to the memory, the touch-sensitive input assembly, the piezoelectric actuator, and the accelerometer to execute a program stored in the memory to monitor signals from the accelerometer and, if a fall is detected based on the signals from the accelerometer, apply a negative voltage to the piezoelectric actuator causing reverse bending of the piezoelectric actuator to permit the stopping arrangement to limit movement of the touch-sensitive input assembly and thereby limit force exerted on the piezoelectric actuator between the touch-sensitive input assembly and the base.

FIELD OF TECHNOLOGY

The present disclosure relates to portable electronic devices thatinclude a touch-sensitive input device including a mechanism forproviding tactile feedback for such input devices and the protection ofthe mechanism for providing tactile feedback.

BACKGROUND

Electronic devices, including portable electronic devices, have gainedwidespread use and can provide a variety of functions including, forexample, telephonic, electronic messaging and other personal informationmanager (PIM) application functions. Portable electronic devices caninclude several types of devices including mobile stations such assimple cellular telephones, smart telephones, wireless PDAs, and laptopcomputers with wireless 802.11 or Bluetooth capabilities.

Devices such as PDAs or smart telephones are generally intended forhandheld use and ease of portability. Smaller devices are generallydesirable for portability. Touch screen assemblies constructed of adisplay, such as a liquid crystal display, with a touch-sensitiveoverlay are useful on such handheld devices as these handheld devicesare small and are therefore limited in space available for user inputand output devices. Further, the screen content on the touch screendevices can be modified depending on the functions and operations beingperformed. Touch screen devices that provide tactile feedback areparticularly advantageous for providing positive feedback upon selectionof a feature on the touch screen.

Such portable electronic devices are commonly mistakenly dropped and areprone to damage as a result. Protection of some components is desirablefor such portable electronic devices in the event of a drop.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the attached Figures, wherein:

FIG. 1 is a simplified block diagram of components including internalcomponents of a portable electronic device according an aspect of anembodiment;

FIG. 2 is a front view of an example of a portable electronic device ina portrait orientation;

FIG. 3 is a sectional side view of portions of the touch screen displayof FIG. 2 (not to scale);

FIG. 4 is a front view of an example of a portable electronic device ina portrait orientation, showing hidden detail in ghost outline;

FIGS. 5A and 5B are sectional side views of portions of the touch screendisplay (not to scale);

FIG. 6 is a functional block diagram of an actuating arrangement of theportable electronic device;

FIG. 7 is a flow chart illustrating a method of controlling a portableelectronic device including a touch-sensitive input surface; and FIG. 8is a flow chart illustrating a method of protecting components of theportable electronic device according to an embodiment.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where considered appropriate, reference numerals may be repeated amongthe figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein may be practiced without these specificdetails. In other instances, well-known methods, procedures andcomponents have not been described in detail so as not to obscure theembodiments described herein. Also, the description is not to beconsidered as limited to the scope of the embodiments described herein.

The disclosure generally relates to an electronic device, which in theembodiments described herein is a portable electronic device. Examplesof portable electronic devices include mobile, or handheld, wirelesscommunication devices such as pagers, cellular phones, cellularsmart-phones, wireless organizers, personal digital assistants,wirelessly enabled notebook computers and the like.

The portable electronic device may be a two-way communication devicewith advanced data communication capabilities including the capabilityto communicate with other portable electronic devices or computersystems through a network of transceiver stations. The portableelectronic device may also have the capability to allow voicecommunication. Depending on the functionality provided by the portableelectronic device, it may be referred to as a data messaging device, atwo-way pager, a cellular telephone with data messaging capabilities, awireless Internet appliance, or a data communication device (with orwithout telephony capabilities). The portable electronic device may alsobe a portable device without wireless communication capabilities as ahandheld electronic game device, digital photograph album, digitalcamera and the like.

Reference is made to the Figures to describe an embodiment of a portableelectronic device that includes a touch-sensitive input assembly that isspaced from and moveable relative to the base. A stopping arrangementlimits movement of the touch-sensitive input assembly in the directionof the base. An actuating arrangement including a piezo disk actuator isdisposed between the touch-sensitive input assembly and the base forselectively receiving an applied voltage to thereby apply a force to thetouch-sensitive input assembly. An accelerometer and functionalcomponents are housed within the housing. The functional componentsinclude a memory and a microprocessor operably connected to the memory,the touch-sensitive input assembly, the piezo disk actuator, and theaccelerometer for executing a program stored in the memory formonitoring signals from the accelerometer and, if a fall is detectedbased on the signals from the accelerometer, applying a negative voltageto the piezo disk actuator causing reverse bending of the piezo diskactuator to permit the stopping arrangement to limit movement of thetouch-sensitive input assembly and thereby limit force exerted on thepiezo disk actuator between the touch-sensitive input assembly and thebase.

Referring to FIG. 1, there is shown therein a block diagram of anexample of an embodiment of a portable electronic device 20. Theportable electronic device 20 includes a number of components such asthe processor 22 that controls the overall operation of the portableelectronic device 20. Communication functions, including data and voicecommunications, are performed through a communication subsystem 24. Datareceived by the portable electronic device 20 can be decompressed anddecrypted by a decoder 26, operating according to any suitabledecompression techniques (e.g. YK decompression, and other knowntechniques) and encryption techniques (e.g. using an encryptiontechnique such as Data Encryption Standard (DES), Triple DES, orAdvanced Encryption Standard (AES)). The communication subsystem 24receives messages from and sends messages to a wireless network 1000. Inthis embodiment of the portable electronic device 20, the communicationsubsystem 24 is configured in accordance with the Global System forMobile Communication (GSM) and General Packet Radio Services (GPRS)standards. The GSM/GPRS wireless network is used worldwide. Newstandards, such as Enhanced Data GSM Environment (EDGE) and UniversalMobile Telecommunications Service (UMTS) are believed to havesimilarities to the network behavior described herein, and it will alsobe understood by persons skilled in the art that the embodimentsdescribed herein are intended to use any other suitable standards thatare developed in the future. The wireless link connecting thecommunication subsystem 24 with the wireless network 1000 represents oneor more different Radio Frequency (RF) channels, operating according todefined protocols specified for GSM/GPRS communications. With newernetwork protocols, these channels are capable of supporting both circuitswitched voice communications and packet switched data communications.

Although the wireless network 1000 associated with the portableelectronic device 20 is a GSM/GPRS wireless network in one exampleimplementation, other wireless networks may also be associated with theportable electronic device 20 in variant implementations. The differenttypes of wireless networks that may be employed include, for example,data-centric wireless networks, voice-centric wireless networks, anddual-mode networks that can support both voice and data communicationsover the same physical base stations. Combined dual-mode networksinclude, but are not limited to, Code Division Multiple Access (CDMA) orCDMA2000 networks, GSM/GPRS networks (as mentioned above), and futurethird-generation (3G) networks like EDGE and UMTS. Some other examplesof data-centric networks include WiFi 802.11, Mobitex™ and DataTAC™network communication systems. Examples of other voice-centric datanetworks include Personal Communication Systems (PCS) networks like GSMand Time Division Multiple Access (TDMA) systems.

The processor 22 also interacts with additional subsystems such as aRandom Access Memory (RAM) 28, a flash memory 30, a display 32 with atouch-sensitive overlay 34 connected to an electronic controller 36 thattogether make up a touch-sensitive display 38, an actuating arrangement,an accelerometer 40, an auxiliary input/output (I/O) subsystem 41, adata port 42, a speaker 44, a microphone 46, short-range communications48 and other device subsystems 50. The touch-sensitive overlay 34 andthe display device 32 provide a touch-sensitive display 38 and theprocessor 22 interacts with the touch-sensitive overlay 34 via theelectronic controller 36.

Some of the subsystems of the portable electronic device 20 performcommunication-related functions, whereas other subsystems may provide“resident” or on-device functions. By way of example, the display 32 andthe touch-sensitive overlay 34 may be used for bothcommunication-related functions, such as entering a text message fortransmission over the network 1000, and device-resident functions suchas a calculator or task list.

The accelerometer 40 includes a cantilever beam with a proof mass andsuitable deflection sensing circuitry. The accelerometer 40 is used fordetecting direction of gravitational forces (or gravity-induced reactionforces). Movement of the portable electronic device 20 to alternateorientations is detected and the orientation of the accelerometer 40 andtherefore of the portable electronic device 20 can be determined.Further, movement of the portable electronic device 20 can be detectedincluding, for example a drop event if the portable electronic device 20is dropped.

The portable electronic device 20 can send and receive communicationsignals over the wireless network 1000 after network registration oractivation procedures have been completed. Network access is associatedwith a subscriber or user of the portable electronic device 20. Toidentify a subscriber according to the present embodiment, the portableelectronic device 20 uses a SIM/RUIM card 52 (i.e. Subscriber IdentityModule or a Removable User Identity Module) inserted into a SIM/RUIMinterface 54 for communication with a network such as the network 1000.The SIM/RUIM card 52 is one type of a conventional “smart card” that canbe used to identify a subscriber of the portable electronic device 20and to personalize the portable electronic device 20, among otherthings. In the present embodiment the portable electronic device 20 isnot fully operational for communication with the wireless network 1000without the SIM/RUIM card 52. By inserting the SIM/RUIM card 52 into theSIM/RUIM interface 54, a subscriber can access all subscribed services.Services may include: web browsing and messaging such as e-mail, voicemail, Short Message Service (SMS), and Multimedia Messaging Services(MMS). More advanced services may include: point of sale, field serviceand sales force automation. The SIM/RUIM card 52 includes a processorand memory for storing information. Once the SIM/RUIM card 52 isinserted into the SIM/RUIM interface 54, it is coupled to the processor22. In order to identify the subscriber, the SIM/RUIM card 52 caninclude some user parameters such as an International Mobile SubscriberIdentity (IMSI). An advantage of using the SIM/RUIM card 52 is that asubscriber is not necessarily bound by any single physical portableelectronic device. The SIM/RUIM card 52 may store additional subscriberinformation for a portable electronic device as well, including datebook(or calendar) information and recent call information. Alternatively,user identification information can also be programmed into the flashmemory 30.

The portable electronic device 20 is a battery-powered device andincludes a battery interface 56 for receiving one or more rechargeablebatteries 58. In at least some embodiments, the battery 58 can be asmart battery with an embedded microprocessor. The battery interface 56is coupled to a regulator (not shown), which assists the battery 58 inproviding power V+ to the portable electronic device 20. Althoughcurrent technology makes use of a battery, future technologies such asmicro fuel cells may provide the power to the portable electronic device20.

The portable electronic device 20 also includes an operating system 60and software components 62 which are described in more detail below. Theoperating system 60 and the software components 62 that are executed bythe processor 22 are typically stored in a persistent store such as theflash memory 30, which may alternatively be a read-only memory (ROM) orsimilar storage element (not shown). Those skilled in the art willappreciate that portions of the operating system 60 and the softwarecomponents 62, such as specific software applications 64, 66, 68, 70 and72, or parts thereof, may be temporarily loaded into a volatile storesuch as the RAM 28. Other software components can also be included, asis well known to those skilled in the art.

The subset of software components 62 that control basic deviceoperations, including data and voice communication applications, willnormally be installed on the portable electronic device 20 during itsmanufacture. Other software applications include a message application64 that can be any suitable software program that allows a user of theportable electronic device 20 to send and receive electronic messages.Various alternatives exist for the message application 64 as is wellknown to those skilled in the art. Messages that have been sent orreceived by the user are typically stored in the flash memory 30 of theportable electronic device 20 or some other suitable storage element inthe portable electronic device 20. In at least some embodiments, some ofthe sent and received messages may be stored remotely from the device 20such as in a data store of an associated host system that the portableelectronic device 20 communicates with.

The software components 62 can further include a device state module 66,a Personal Information Manager (PIM) 68, and other suitable modules (notshown). The device state module 66 provides persistence, i.e. the devicestate module 66 ensures that important device data is stored inpersistent memory, such as the flash memory 30, so that the data is notlost when the portable electronic device 20 is turned off or losespower.

The PIM 68 includes functionality for organizing and managing data itemsof interest to the user, such as, but not limited to, e-mail, contacts,calendar events, voice mails, appointments, and task items. The PIM 68has the ability to send and receive data items via the wireless network1000. PIM data items may be seamlessly integrated, synchronized, andupdated via the wireless network 1000 with the portable electronicdevice subscriber's corresponding data items stored and/or associatedwith a host computer system. This functionality creates a mirrored hostcomputer on the portable electronic device 20 with respect to suchitems. This can be particularly advantageous when the host computersystem is the portable electronic device subscriber's office computersystem.

The software components 62 also includes a connect module 70, and aninformation technology (IT) policy module 72. The connect module 70implements the communication protocols that are required for theportable electronic device 20 to communicate with the wirelessinfrastructure and any host system, such as an enterprise system, thatthe portable electronic device 20 is authorized to interface with.

The connect module 70 includes a set of APIs that can be integrated withthe portable electronic device 20 to allow the portable electronicdevice 20 to use any number of services associated with the enterprisesystem. The connect module 70 allows the portable electronic device 20to establish an end-to-end secure, authenticated communication pipe withthe host system. A subset of applications for which access is providedby the connect module 70 can be used to pass IT policy commands from thehost system to the portable electronic device 20. This can be done in awireless or wired manner. These instructions can then be passed to theIT policy module 72 to modify the configuration of the device 20.Alternatively, in some cases, the IT policy update can also be done overa wired connection.

Other types of software applications can also be installed on theportable electronic device 20. These software applications can be thirdparty applications, which are added after the manufacture of theportable electronic device 20. Examples of third party applicationsinclude games, calculators, utilities, etc.

The additional applications can be loaded onto the portable electronicdevice 20 through at least one of the wireless network 1000, theauxiliary I/O subsystem 41, the data port 42, the short-rangecommunications subsystem 48, or any other suitable device subsystem 50.This flexibility in application installation increases the functionalityof the portable electronic device 20 and may provide enhanced on-devicefunctions, communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using the portableelectronic device 20.

The data port 42 enables a subscriber to set preferences through anexternal device or software application and extends the capabilities ofthe portable electronic device 20 by providing for information orsoftware downloads to the portable electronic device 20 other thanthrough a wireless communication network. The alternate download pathmay, for example, be used to load an encryption key onto the portableelectronic device 20 through a direct and thus reliable and trustedconnection to provide secure device communication.

The data port 42 can be any suitable port that enables datacommunication between the portable electronic device 20 and anothercomputing device. The data port 42 can be a serial or a parallel port.In some instances, the data port 42 can be a USB port that includes datalines for data transfer and a supply line that can provide a chargingcurrent to charge the battery 58 of the portable electronic device 20.

The short-range communications subsystem 48 provides for communicationbetween the portable electronic device 20 and different systems ordevices, without the use of the wireless network 1000. For example, theshort-range communications subsystem 48 may include an infrared deviceand associated circuits and components for short-range communication.Examples of short-range communication standards include standardsdeveloped by the Infrared Data Association (IrDA), Bluetooth, and the802.11 family of standards developed by IEEE.

In use, a received signal such as a text message, an e-mail message, orweb page download is processed by the communication subsystem 24 andinput to the processor 22. The processor 22 then processes the receivedsignal for output to the display 32 or alternatively to the auxiliaryI/O subsystem 41. A subscriber may also compose data items, such ase-mail messages, for example, using the touch-sensitive overlay 34 onthe display 32 that are part of the touch-sensitive display 38, andpossibly the auxiliary I/O subsystem 41. The auxiliary I/O subsystem 41may include devices such as: a mouse, track ball, infrared fingerprintdetector, or a roller wheel with dynamic button pressing capability. Acomposed item may be transmitted over the wireless network 1000 throughthe communication subsystem 24.

For voice communications, the overall operation of the portableelectronic device 20 is substantially similar, except that the receivedsignals are output to the speaker 44, and signals for transmission aregenerated by the microphone 46. Alternative voice or audio I/Osubsystems, such as a voice message recording subsystem, can also beimplemented on the portable electronic device 20. Although voice oraudio signal output is accomplished primarily through the speaker 44,the display 32 can also be used to provide additional information suchas the identity of a calling party, duration of a voice call, or othervoice call related information.

Reference is now made to the FIG. 2, there is shown a front view of anexample of a portable electronic device 20 in portrait orientation. Theportable electronic device 20 includes a housing 74 that houses internalcomponents including internal components shown in FIG. 1 and frames thetouch screen display 38 such that the touch screen display 38 is exposedfor user-interaction therewith when the portable electronic device 20 isin use. It will be appreciated that the touch screen display 38 mayinclude any suitable number of user-selectable features renderedthereon, for example, in the form of virtual buttons for user-selectionof, for example, applications, options, or keys of a keyboard for userentry of data during operation of the portable electronic device 20.

The touch screen display 38 can be any suitable touch screen displaysuch as a capacitive touch screen display. A capacitive touch screendisplay includes the display 32 and the touch-sensitive overlay 34, asshown in FIG. 1, in the form of a capacitive touch-sensitive overlay. Itwill be appreciated that the touch-sensitive overlay 34 in the form of acapacitive touch-sensitive overlay is an assembly of a number of layersin a stack and is fixed to the display 32 via a suitable optically clearadhesive. The layers can include, for example a substrate fixed to theLCD display 32 by a suitable adhesive, a ground shield layer, a barrierlayer, a pair of capacitive touch sensor layers separated by a substrateor other barrier layer, and a cover layer fixed to the second capacitivetouch sensor layer by a suitable adhesive. The capacitive touch sensorlayers can be any suitable material such as patterned indium tin oxide(ITO).

In the present example, the X and Y location of a touch event are bothdetermined with the X location determined by a signal generated as aresult of capacitive coupling with one of the touch sensor layers andthe Y location determined by the signal generated as a result ofcapacitive coupling with the other of the touch sensor layers. Each ofthe touch-sensor layers provides a signal to the controller 36 as aresult of capacitive coupling with a suitable object such as a finger ofa user resulting in a change in the electric field of each of the touchsensor layers. The signals represent the respective X and Y touchlocation values. It will be appreciated that other attributes of theuser's touch on the touch screen display 38 can be determined. Forexample, the size and the shape of the touch on the touch screen display38 can be determined in addition to the location (X and Y values) basedon the signals received at the controller 36 from the touch sensorlayers.

Referring still to FIG. 2, it will be appreciated that a user's touch onthe touch screen display 38 is determined by determining the X and Ytouch location and user-selected input is determined based on the X andY touch location and the application executed by the processor 22. Thusa feature such as a virtual button displayed on the touch screen display38 may be selected by matching the feature to the X and Y location of atouch event on the touch screen display 38. A feature selected by theuser is determined based on the X and Y touch location and theapplication.

The housing 74 can be any suitable housing for the internal componentsshown in FIG. 1. As best shown in FIG. 3, the housing 74 in the presentexample includes a back 76, a frame 78, which frames the touch screendisplay 38 and sidewalls 80 that extend between and generallyperpendicular to the back 76 and the frame 78. A base 82 is spaced fromand is generally parallel to the back 76. The base 82 can be anysuitable base and can include, for example, a printed circuit board orflex circuit board supported by a stiff support between the base 82 andthe back 76. The back 76 includes a plate (not shown) that is releasablyattached for insertion and removal of, for example, the battery 58 andthe SIM/RUIM card 52 described above. It will be appreciated that theback 76, the sidewalls 80 and the frame 78 can be injection molded, forexample. In the example of the portable electronic device 20 shown inFIG. 2, the frame 78 is generally rectangular with rounded cornersalthough other shapes are possible.

The display 32 and the touch-sensitive overlay 34 can be supported on asupport tray 84 of suitable material such as magnesium for providingmechanical support to the display 32 and touch-sensitive overlay 34. Acompliant gasket 86 can be located around the perimeter of the frame 78,between an upper portion of the support tray 84 and the frame 78 toprovide a gasket for protecting the components housed in the housing 74of the portable electronic device 20. A suitable material for thecompliant gasket 86 includes, for example, a cellular urethane foam forproviding shock absorption, vibration damping and a suitable fatiguelife. The touch screen display 38 is moveable within the housing 74 asthe touch screen display 38 can be moved away from the base 82, therebycompressing the compliant gasket 86, for example. Further, the touchscreen display 38 can be moved toward the base 82, thereby compressingthe protrusion 92 and applying a force to the piezo disk actuators 90referred to below. FIG. 3 shows the touch screen display 38 absent anexternal applied force by a user's finger, for example, during a touchevent and with the actuating arrangement 39 absent actuation. FIG. 3 andFIGS. 5A and 5B are not drawn to scale for the purpose of illustrationof the actuating arrangement 39 including the piezo disk actuators 90,and the operation of the actuating arrangement 39.

In the present example, the actuating arrangement 39 includes four piezodisk actuators 90, with each piezo disk actuator 90 supported on arespective protrusion 92. Each protrusion 92 is a cylindrical protrusionon which a respective piezo disk actuator 90 is mounted such that theprotrusion 92 engages the respective disk actuator 90 proximal thecenter of the piezo disk actuator 90. Each protrusion 92 may be made ofany suitable material such as a hard rubber and is located between thepiezo disk actuator 90 and the base 82. The piezo disk actuators 90 areeach located proximal a respective corner of the touch screen display38, as shown in FIG. 4, on a respective protrusion 92.

Support rings 94 extend from the support tray 84, toward the base 82,each one of the support rings 94 for engaging a respective piezo diskactuator 90 while permitting flexing of the piezo disk actuator 90. Thesupport rings 94 may be made of any suitable material and may be part ofthe support tray 84 or may connected to the support tray 84.

As best shown in FIG. 3, each piezo disk actuator 90 includes apiezoelectric disk 96 such as a PZT ceramic disk adhered to a metalsubstrate 98 of larger diameter than the piezoelectric disk 96 forbending when the piezoelectric disk 96 expands or contracts as a resultof build up of charge at the piezoelectric disk 96. Each piezo diskactuator 90 is supported on the respective protrusion 92 on one side ofthe base 82, proximal a respective corner of the housing 74 with eachsupport ring 94 sized such that the edge of the metal substrate 98contacts the support ring 94 and permits flexing of the piezo diskactuator 90. Thus, each support ring 94 engages a respective piezo diskactuator 90 near a perimeter of the piezo disk actuator 90. A respectiveforce sensor 100 is located between each protrusion 92 and therespective piezo disk actuator 90. A suitable force sensor 100 includes,for example, a puck-shaped force sensing resistor for measuring appliedforce (or pressure). It will be appreciated that a force can bedetermined using a force sensing resistor as an increase in pressure onthe force sensing resistor results in a decrease in resistance (orincrease in conductance).

In the portable electronic device 20, each piezo disk actuator 90 islocated between the base 82 and the support tray 84 and force is appliedon each piezo disk actuator 90 by the touch screen display 38, in thedirection of the base 82, causing bending of the piezo disk actuator 90.Thus, absent an external force applied by the user, for example bypressing on the touch screen display 38, and absent a charge on thepiezo disk actuator 90, the piezo disk actuator 90 undergoes a slightbending or preload as shown in FIG. 3. An external applied force in theform of a user pressing on the touch screen display 38 during a touchevent, and prior to actuation of the piezo disk actuator 90, causesincreased bending of the piezo disk actuator 90 and the piezo diskactuator 90 applies a spring force against the touch screen display 38.When the piezoelectric disk 96 of the present example is charged, thepiezoelectric disk 96 expands and causes the metal substrate 94 andpiezoelectric disk 96 to apply a further force, opposing the externalapplied force, on the touch screen display 38 as the piezo actuator 90straightens. The piezo actuator 90 may not straigten completely or evento the preloaded position shown in FIG. 3 as the external applied forcemay be greater than the force applied to the touch screen display 38 bythe piezo actuators 90.

In the present embodiment each piezo disk actuator 90 is in contact withthe respective support ring 94 which is part of or connected to thesupport tray 84. Thus, depression of the touch screen display 38 by userapplication of a force thereto is determined by a change in resistanceat the force sensors 100 and causes further bending of the piezo diskactuators 90. Further, the charge on each piezo disk actuator 90 can bemodulated to control the force applied by the piezo disk actuator 90 onthe support ring 94 and the resulting movement of the touch screendisplay 38. The charge can be modulated by modulating the appliedvoltage or current. For example, a current can be applied to increasethe charge on the piezo disk actuator 90 to provide an applied voltageacross the piezo disk actuator 90 and to expand the piezoelectric disk96 as described above, causing the metal substrate 94 and thepiezoelectric disk 96 to straighten as referred to above. The chargetherefore results in the force on the touch screen display 38 foropposing the external applied force and movement of the touch screendisplay 38 away from the base 82. The charge on the piezo disk actuator90 can also be removed via a controlled discharge current causing thepiezoelectric disk 96 to contract again, releasing the force caused bythe electric charge and thereby decreasing the force on the touch screendisplay 38, permitting the touch screen display to return to a restposition, or preloaded position shown in FIG. 3. As indicated above, themovement of the touch screen display 38 and the flexing of the piezodisk actuators 90 is very small.

The applied current can also be reversed to provide a negative appliedvoltage across each piezo disk actuator 90 and to contract eachpiezoelectric disk 96 to cause the respective metal substrate andpiezoelectric disk 96 to bend in the reverse direction, away from thetouch screen display 38, such that each protrusion 92 is located on aconcave side of the respective piezo disk actuator 90 and each piezodisk actuator 90 is not in contact with the respective support ring 94,as best shown in FIGS. 5A and 5B. The piezo disk actuator 90 istherefore reverse charged and the reverse charge on the piezo diskactuator 90 can be removed via a controlled current causing thepiezoelectric disk 96 to expand again, releasing the force caused by theelectric charge and therefore returning to the preloaded position shownin FIG. 3.

A stopping arrangement 102 is also located between the support tray 84and the base 82 for limiting movement of the touch screen display 38 andsupport tray 84 in the direction of the base 82. In the presentembodiment, the stopping arrangement 102 includes a plurality ofcylindrical rings extending from the base 82 and sized to permitmovement of the touch screen display 38 and support tray 84 as describedabove while limiting movement in the direction of the base 82 so thatexcessive force is not applied to the piezo disk actuators 90 when bentin the reverse direction as described above with reference to FIGS. 5Aand 5B. The cylindrical ring can be any suitable material such as a hardrubber. Each one of the cylindrical rings extends around a respectiveone of the piezo disk actuators 90 and therefore provides protection fora respective one of the piezo disk actuators 90 as movement of the touchscreen display 38, support tray 84 and support ring 94 toward the base82 is limited.

In the present example, a reverse voltage applied across the piezo diskactuators 90 causes bending of the piezo disk actuators 90 as shown inFIG. 5A. Movement of the touch screen display 38, support tray 84 andsupport ring 94 is limited such when a force is applied to cause thetouch screen display 38 to move toward the base 82, the support tray 84contacts the cylindrical rings of the stopping arrangement 90 ratherthan the support rings 94 contacting the respective piezo disk actuators90 as shown in FIG. 5B. Again, movement of the touch screen display 38and the bending of the piezo disk actuators 90 is exaggerated in FIGS.5A and 5B for the purpose of illustration.

FIG. 6 shows the actuating arrangement 39 according to one embodiment.As shown, each of the piezo disk actuators 90 is connected to a piezodriver 104 that communicates with a microprocessor 106 including afour-channel amplifier and analog-to-digital converter 108 that isconnected to each of the force sensors 100. The microprocessor 106 isalso in communication with the main processor 22 of the portableelectronic device 20. The microprocessor 106 can provide signals to themain processor 22 of the portable electronic device 20. It will beappreciated that the piezo driver 104 can be embodied in drive circuitrybetween the microprocessor 106 and the piezoelectric disks 96.

The mechanical work performed by the piezo disk actuator 90 can becontrolled to provide generally consistent force and movement of thetouch screen display 38 in response to detection of an applied force onthe touch screen display 38 in the form of a touch, for example.Fluctuations in mechanical work performed as a result of, for example,temperature, can be reduced by modulating the current to control thecharge. Those skilled in the art will appreciate that each piezoelectricdisk 96 has similar electrical properties to a capacitor. The mechanicalwork performed (force*displacement) by the peizo disk actuator 90 can becontrolled by controlling the charge, expressed as:

Q _(piezo) =C _(piezo) *V _(piezo)

where: Q is charge;

-   -   C is capacitance; and    -   V is voltage.

A coefficient, referred to as the D31 coefficient of a piezoelectricmaterial composition provides the relationship between voltage andforce. The D31 coefficient and the relative dielectric constant, (Er) ofa given piezoelectric material composition vary inversely withtemperature, however. Therefore, if the charge of the piezoelectric disk96 is controlled within a small range, the variance of the mechanicalwork of the piezo disk actuator 90 can be small. The current can becontrolled as the current flowing in or out of a capacitor (which hassimilar electrical properties to the piezoelectric disk 96) is given by:

I=C*dV/dT

where I is current;

-   -   C is capacitance; and    -   dV/dT is differential voltage or instantaneous rate of voltage        change.        With I and dT held constant, then as C decreases, dV increases.        Thus the charge is controlled since        Q_(piezo)=C_(piezo)*V_(piezo).

The microprocessor 106 controls the piezo driver 104 for controlling thecurrent to the piezoelectric disks 96 and thereby controlling thecharge, increasing the charge to increase the force on the touch screendisplay 38 away from the base 82 and decreasing the charge to decreasethe force on the touch screen display 38, permitting the touch screendisplay 38 to move toward the base 82. Further, the microprocessor 106controls the piezo driver 104 for controlling the current, to reversethe current to the piezoelectric disks 96, and thereby reversing thecharge to cause flexing (referred to above as bending) of thepiezoelectric disks 96 and respective metal substrates 98 away from thetouch screen display 38, as described above.

In the present example, each of the piezo disk actuators 90 areconnected to the microprocessor 106 through the piezo driver 104 and areall controlled equally and concurrently. It will be appreciated that thepiezo disk actuators 90 can be controlled separately, however.

The portable electronic device 20 can also include physical buttons. Inthe present example, the portable electronic device 20 includes fourphysical buttons 110, 112, 114,116 in the housing 74 for user-selectionfor performing functions or operations including an “off-hook” button110 for placing an outgoing cellular telephone call or receiving anincoming cellular telephone call, a Menu button 112 for displaying acontext-sensitive menu or submenu, an escape button 114 for returning toa previous screen or exiting an application, and an “on-hook” button 116for ending a cellular telephone call. Further buttons for performingfurther functions on the portable electronic device of FIG. 4 may bevirtual features rendered on the touch screen display 38.

The portable electronic device 20 is controlled generally by monitoringthe touch screen display 38 for a touch event thereon, and modulating aforce on the touch screen display 38 for causing a first movement of thetouch screen display 38 relative to the base 82 of the portableelectronic device 20 in response to detection of a touch event. Theforce is applied by at least one of the piezo disk actuators 90, in asingle direction on the touch-sensitive input surface of the touchscreen display 38.

Reference is made to FIG. 7 to describe a method of controlling aportable electronic device 20. It will be appreciated that the steps ofFIG. 7 can be carried out by routines or subroutines of softwareexecuted by, for example, the microprocessor 106. Coding of software forcarrying out such steps is well within the scope of a person of ordinaryskill in the art having regard to the present description.

The method starts with, for example, the portable electronic device 20turned to an on or awake state (step 200). The touch screen display 38is monitored for a touch event (step 210) and, in response todetermination of a touch event, the charge at each of the piezoelectricdisks 96 is modulated to modulate the force applied by the piezoelectricactuator 90 on the touch screen display 38 to cause movement of thetouch screen display 38 for simulating the collapse of a dome-typeswitch (step 220). When the end of the touch event is detected (step230), the charge at each of the piezoelectric disks 96 is modulated tomodulate the force applied by the piezoelectric actuators 90 to thetouch screen display 38 to cause movement of the touch screen display 38for simulating release of a dome-type switch (step 240). The processends at step 250. The force is applied by at least one of thepiezoelectric actuators 90 in a one direction on the touch-sensitiveinput surface of the touch screen display 38.

It will be appreciated that the flow chart of FIG. 7 is simplified forthe purpose of explanation. A further touch event can be detected againand the steps can be repeated, for example. Further, more than one touchevent can occur such that a second touch event can be detected prior tothe end of a first touch event. Thus, the charge at each of thepiezoelectric disks 96 can be modulated again to modulate the forceapplied by the piezoelectric actuators 90 to the touch screen display 38to cause movement of the touch screen display 38 for simulating anothercollapse of a dome-type switch prior to the end of the first touch eventbeing detected. Similarly, the end of a first one of the touch eventscan be detected and the charge at each of the piezoelectric disks 96modulated to modulate the force applied by the piezoelectric actuators90 to cause movement of the touch screen display 38 for simulatingrelease of a dome-type switch followed by the end of the second one ofthe touch events being detected and the charge at each of thepiezoelectric disks 96 again modulated to modulate the force applied bythe piezoelectric actuators to cause movement of the touch screendisplay 38 for simulating release of a dome-type switch. Therefore,collapse of a dome-type switch can be simulated multiple times insuccession prior to simulation of release of a dome-type switch. Therelease can also be simulated multiple times in succession. Thesuccessive simulations can occur rapidly. Further still, multipledome-type switch collapses in succession can be simulated based on theexternal applied force. For example, a first simulation of collapse of adome-type switch can occur at a threshold external applied force and asecond simulation of collapse of a dome-type switch can occur at asecond, higher threshold external applied force to provide multiplecollapse events.

Continued reference is made to FIG. 8 to describe an example of themethod of controlling a portable electronic device in accordance withthe present embodiment. The portable electronic device 20 is turned toan on or awake state in any suitable manner (step 400). In the on orawake state, user-selectable features are rendered on the touch screendisplay 38. Such user-selectable features can include, for example,icons for selection of an application for execution by the processor 22,buttons for selection of user options, keys of a virtual keyboard,keypad or any other suitable user-selectable icons or buttons.

A force on the touch screen display 38 is detected through the forcesensors 100, as a result of a change in resistance at the forcesensitive resistors. The force is determined at the microprocessor 106as a result of signals from the amplifier and four-channel analog todigital converter 108 connected to each of the force sensors 100. Thus,the touch screen display 38 is monitored for a touch event and a touchevent on the touch screen display 38 can be detected. Such a touch eventcan be determined upon determination of an external applied force as aresult of a user touch at the touch screen display 38 for selection of,for example, an Internet browser application, an email application, acalendar application, or any other suitable application, option, orother feature within an application (step 210). For the purpose of thepresent example, the touch event is detected when the force measured atthe force sensors 100 exceeds a minimum threshold force. Thus, themeasured force at the force sensors 100 is compared to a threshold forceand a touch event is detected if the measured force is determined toexceed the threshold force. Conversely, a touch event is not detected asa result of a relatively light touch or brush on the touch screendisplay 38 with a measured force that is lower than the threshold force.It will be appreciated that the touch-sensitive input surface 34 isthereby monitored for a touch event.

In response to detection of the touch event at step 210, a suitablecurrent is applied to the piezo disk actuator 90, ramping up the chargeover a period of time causing flexing of the piezo disk actuator 90 anda resulting force applied to the touch screen display 38 through thesupport tray 84. The charge is ramped up over a period of time so thatthe user does not detect the force applied by the piezo disk actuators90 on the touch screen display 38. Next, the electrical charge isreduced by a suitable controlled discharge current and the resultingforce applied by the piezo disk actuator 90 on the touch screen display38 is reduced over a very short period of time relative to the period oftime for ramping up the charge, for simulating collapse of a dome-typeswitch (step 220).

Next, the end of the touch event is detected (step 230). When themeasured force at the force sensors is reduced to a force below apredetermined force, the end of the touch event is detected. Thepredetermined force can be lower than the threshold force describedabove for reducing the chance of false detection of an end of a touchevent and successive start of another touch event if the externalapplied force hovers such that the measured force hovers at about thethreshold applied force. A suitable current is applied to the piezo diskactuator 90, causing an increase in charge, flexing of the piezo diskactuator 90 and a resulting force to be applied to the touch screendisplay 38 through the support tray 84 over a relatively short period oftime compared to the period of time for ramping up the charge, forsimulating release of a dome-type switch (step 240). Next, theelectrical charge is reduced and the resulting force applied by thepiezo disk actuator 90 on the touch screen display 38 is reduced byramping down over a long period of time compared to the period of timefor increasing charge to simulate release.

The charge and discharge current applied to the piezoelectric disk 96 istherefore modulated to modulate the force from the piezo disk actuators90 on the touch screen display 38 for providing a desirable tactilefeedback by simulating collapse of a dome-type switch in response todetection of the touch event and by simulating release of a dome-typeswitch upon detection of an end of the touch event.

The process ends at step 250.

The microprocessor 106 can provide a signal to the main processor 22 ofthe portable electronic device 20 when the measured force at the forcesensors 100 as a result of the external applied force exceeds thethreshold. Similarly, the microprocessor 100 can provide a signal to themain processor 22 of the portable electronic device 20 when the externalapplied force is reduced so that the measured force at the force sensors100 falls below the predetermined force. Thus, the main processor 22 ofthe portable electronic device 20 can receive input from the actuatingarrangement 39. Further, the main processor 22 can communicate with themicroprocessor 106 to control the microprocessor 106 and thereby controlthe actuating arrangement 39. Thus, the overall operation can becontrolled by the processor 22.

Reference is now made to FIG. 8 to describe the operation of theportable electronic device 20 in accordance with an embodiment. It willbe appreciated that the steps of FIG. 8 can be carried out by routinesor subroutines of software executed by, for example, the processor 22and the microprocessor 106. Coding of software for carrying out suchsteps is well within the scope of a person of ordinary skill in the arthaving regard to the present description.

The accelerometer 40 is polled for signals to determine status of theportable electronic device 20 (step 300). If a fall is not detected(step 310), the method returns to step 300 where the accelerometer 40 isagain polled. If a fall is detected as a result of, for example,dropping the portable electronic device 20, the fall is determined basedon the signals from the accelerometer (step 310) and the method proceedsto step 320. A reverse voltage is applied across the piezo diskactuators 90 over a very short period of time. A reverse voltage isapplied across the piezo disk actuators 90 by reversing the appliedcurrent to negatively charge each piezoelectric disk 96. Eachpiezoelectric disk 96 contracts as a result of the negative charge andeach metal substrate 98 and respective piezoelectric disk 96 flexes bybending away from the touch screen display 38. Next, the accelerometer40 is again polled (step 330) and if it is determined at step 340 thatthe fall has not yet ended based on the signals from the accelerometer40, the method returns to step 330. If, however, it is determined thatthe fall has ended at step 340, the reverse charge on each of thepiezoelectric disks 96 is discharged, to return the piezoelectric disksto the uncharged state. The method then returns to step 300 where theaccelerometer 40 is again polled.

It will be appreciated that the flow chart of FIG. 8 is simplified forthe purpose of explanation. Further steps and substeps may occur thatare not described herein.

Continued reference is made to FIG. 8 to describe an example of theembodiment shown. The present example is provided for the purpose ofillustration. As indicated, the accelerometer 40 is polled for statussignals (step 300). In the present example, the main processor 22 pollsthe accelerometer 40. The signals are analyzed at the main processor 22and it is determined if the portable electronic device 20 is falling,for example, as a result of being dropped (step 310). According to thepresent example, the processor 22 polls the accelerometer 40. A fall ordrop can be determined based on the signals from the accelerometer 40resulting from the acceleration produced by gravity. If a drop is notdetected, the method returns to step 300 where the accelerometer 40 isagain polled by the main processor 22. Thus, portable electronic device20 continually monitors for a drop or fall.

If a fall is detected as a result of, for example, dropping the portableelectronic device 20, the fall is determined based on the signals fromthe accelerometer (step 310) and the method proceeds to step 320. In thepresent example, the main processor 22 sends a signal to themicroprocessor 106 for application of the reverse voltage. Themicroprocessor 106 controls the piezo driver 104 for driving the piezodisk actuators 90. A reverse voltage is applied across the piezo diskactuators 90 over a very short period of time. For example, in a systemin which four 75 nF piezoelectric disks 96 have a current chargingcapability of 50 mA, a 50 mA charge current applied at 100% duty cycleand 300 nF of capacitance charged to 200V, the time to charge is about1.2 mS. Thus, a voltage of up to 200V may be applied to charge the piezodisk actuators over a period of about 1 ms. Alternatively, the voltagemay be applied directly without limiting the charge current to therebycause bending of the piezo disk actuators 90 in a very short period oftime of 30 uS. Thus, the reverse voltage is applied by applying acurrent that is the negative or reverse of the current applied tomodulate the charge to provide tactile feedback on the touch screendisplay 38. Each piezoelectric disk 96 contracts as a result of theapplied voltage and the respective metal substrate 98 and piezoelectricdisk 96 bend in the reverse direction, away from the touch screendisplay 38, such that each protrusion 92 is located on a concave side ofthe respective piezo disk actuator 90 and the piezo disk actuator 90 isnot in contact with the respective support ring 94, as best shown inFIGS. 5A and 5B. Each piezo disk actuator 90 is therefore reversecharged. Thus, when a fall is detected, the piezo disk actuators 90 eachflex away from the touch screen display 38 to permit the stoppingarrangement to limit movement of the touch-sensitive input assembly andthereby limit forces exerted on the piezo disk actuators 90 by movementof the touch screen display 38. If the portable electronic device 20 isdropped such that a force is exerted on the touch screen display 38toward the base 82 as a result of impact of the portable electronicdevice 20 with a surface that the portable electronic device 20 landson, the touch screen display 38 and the support tray 84 can move towardthe base 82 only until stopped by the stopping arrangement 102.

Next, the accelerometer 40 is again polled (step 330) by the mainprocessor and if it is determined at step 340 that the fall has not yetended based on the signals from the accelerometer 40, the method returnsto step 330. If, however, it is determined that the fall has ended atstep 340, the main processor 22 sends a signal to the microprocessor 106for discharging the piezoelectric disks 96. The microprocessor 106controls the piezo driver 104 for driving the piezo disk actuators 90and a suitable current is applied to discharge each piezoelectricactuator 90. Thus, the reverse charge on each of the piezoelectric disks96 is discharged, to return the piezoelectric disks 96 to the unchargedstate, thereby causing each piezoelectric disk 96 to expand again,releasing the force caused by the electric charge and returning thepiezo disk actuators to the preloaded position shown in FIG. 3. Themethod then returns to step 300 where the accelerometer 40 is againpolled.

In the above example, the main processor 22 polls the accelerometer 40and communicates with the microprocessor 106 to control the piezo driver104 for controlling the charge on the piezoelectric disks 96. It will beappreciated that the microprocessor 106 may poll the accelerometerdirectly. Alternatively, the main processor 22 may be connected to thepiezo driver 104. The microprocessor 106 and main processor 22 maytherefore be embodied in a single device.

In the embodiment described above, the piezoelectric disk 96 such as aPZT ceramic disk is adhered to a metal substrate 98. Alternatively, thepiezoelectric disk 96 may be adhered to a suitable ceramic substrate.

The stopping arrangement 102 limits movement of the touch-sensitivedisplay 38, the support tray 84 and the support rings 94 in thedirection of the base 82 and thereby limits forces including tensileforces on the piezoelectric disks 96 caused by the touch screen display38 moving toward the base 82. The piezoelectric disks 96 are thereforeprotected from stresses applied as a result of forces from the touchscreen display 38 upon an impact after dropping the portable electronicdevice 20. Thus, the piezoelectric disks 96 of the portable electronicdevice 20, which may be susceptible to damage as a result of a fall, areprotected.

The actuating arrangement 39 provides a relatively thin device forproviding a desirable tactile feedback to the user without addingsignificantly to the thickness of the portable electronic device 20.Further, the actuating arrangement 39 can be controlled to providetactile feedback upon detection of a touch event such that tactilefeedback that simulates actuation of a dome-type switch is provided foreach touch event. Further, the actuating arrangement 39 can be protectedin the event of a drop or fall.

According to one aspect, there is provided a portable electronic deviceincluding a housing with a base. A touch-sensitive input assembly isspaced from and moveable relative to the base and a stopping arrangementlimits movement of the touch-sensitive input assembly in the directionof the base. An actuating arrangement including a piezoelectric actuatoris disposed between the touch-sensitive input assembly and the base forselectively receiving an applied voltage to thereby apply a force to thetouch-sensitive input assembly. An accelerometer and functionalcomponents are housed within the housing. The functional componentsinclude a memory and a processor operably connected to the memory, thetouch-sensitive input assembly, the piezoelectric actuator, and theaccelerometer for executing a program stored in the memory formonitoring signals from the accelerometer and, if a fall is detectedbased on the signals from the accelerometer, applying a negative voltageto the piezoelectric actuator causing reverse bending of thepiezoelectric actuator to permit the stopping arrangement to limitmovement of the touch-sensitive input assembly and thereby limit forceexerted on the piezoelectric actuator between the touch-sensitive inputassembly and the base.

According to another aspect, there is provided a method of protecting aportable electronic device that includes a housing with a base, atouch-sensitive input assembly spaced from and moveable relative to thebase, a stopping arrangement for limiting movement of thetouch-sensitive input assembly in the direction of the base, anactuating arrangement comprising a piezoelectric actuator disposedbetween the touch-sensitive input assembly and the base for selectivelyreceiving an applied voltage to thereby apply a force to thetouch-sensitive input assembly, an accelerometer housed within thehousing, and functional components in the housing comprising a memoryand a processor operably connected to the memory, the touch-sensitiveinput assembly, the piezoelectric actuator, and the accelerometer. Themethod includes executing a program stored in the memory for monitoringsignals from the accelerometer; and if a fall is detected based on thesignals from the accelerometer, applying a negative voltage to thepiezoelectric actuator causing reverse bending of the piezoelectricactuator to permit the stopping arrangement to limit movement of thetouch-sensitive input assembly and thereby limit force exerted on thepiezoelectric actuator between the touch-sensitive input assembly andthe base.

According to yet another aspect, there is provided a computer-readablemedium having computer-readable code embodied therein for execution by aprocessor in a portable electronic device according to claim 1 forcausing the portable electronic device to monitor signals from theaccelerometer, and if a fall is detected based on the signals from theaccelerometer, apply the negative voltage to the piezoelectric actuatorcausing reverse bending of the piezoelectric actuator to permit thestopping arrangement to limit movement of the touch-sensitive inputassembly and thereby limit force exerted on the piezoelectric actuatorbetween the touch-sensitive input assembly and the base.

Advantageously, the piezoelectric disks are protected from stressesapplied as a result of the touch screen display moving toward the baseupon an impact from dropping the portable electronic device. Impact ofthe portable electronic device causing excessive tension within thepiezoelectric disk may result in failure of the piezoelectric disk. Theapplication of a negative voltage causing reverse bending permits thestopping arrangement to limit movement of the touch-sensitive display inthe direction of the base and thereby limits forces including tensileforces on the piezoelectric disk caused by the touch screen displaymoving toward the base.

The actuating arrangement with the piezoelectric disk provides desirabletactile feedback in response to a touch event on the touch screendisplay. Controlling the piezoelectric actuator or actuators to simulateactuation of a dome-type switch upon touching the touch-sensitive inputsurface provides a desirable tactile feedback for confirming receipt ofinput to the user, thereby providing a positive response and reducingthe chance of input errors such as double entry, decreasing use time andincreasing user-satisfaction. Further, the piezoelectric disk is thin,therefore not adding significantly to the thickness of the device whileproviding a desirable tactile feedback to the user.

While the embodiments described herein are directed to particularimplementations of the portable electronic device and the method ofcontrolling the portable electronic device, it will be understood thatmodifications and variations may occur to those skilled in the art. Allsuch modifications and variations are believed to be within the sphereand scope of the present disclosure.

1. A portable electronic device comprising: a housing including a base;a touch-sensitive input assembly spaced from and moveable relative tothe base; a stopping arrangement to limit movement of thetouch-sensitive input assembly in the direction of the base; anactuating arrangement comprising a piezoelectric actuator disposedbetween the touch-sensitive input assembly and the base to selectivelyreceive an applied voltage to thereby apply a force to thetouch-sensitive input assembly; an accelerometer housed within thehousing; and functional components in the housing comprising a memoryand a processor operably connected to the memory, the touch-sensitiveinput assembly, the piezoelectric actuator, and the accelerometer toexecute a program stored in the memory to apply a negative voltage tothe piezoelectric actuator, if a fall is detected based on signals fromthe accelerometer, cause reverse bending of the piezoelectric actuatorto permit the stopping arrangement to limit movement of thetouch-sensitive input assembly and thereby limit force exerted on thepiezoelectric actuator between the touch-sensitive input assembly andthe base.
 2. The portable electronic device according to claim 1,wherein the piezoelectric actuator comprises a piezo disk actuator. 3.The portable electronic device according to claim 2, wherein the piezodisk actuator comprises a piezoelectric disk adhered to a metal orceramic substrate.
 4. The portable electronic device according to claim2, comprising a protrusion between the base and the touch-sensitiveinput assembly for engaging the piezo disk actuator proximal a center ofthe piezo-disk actuator.
 5. The portable electronic device according toclaim 4, wherein the protrusion extends between the base and the piezodisk actuator.
 6. The portable electronic device according to claim 5,wherein the piezo disk actuator is mounted on the protrusion.
 7. Theportable electronic device according to claim 3, wherein the protrusionis disposed on the concave side of the piezo disk actuator duringapplication of the negative voltage causing reverse bending.
 8. Theportable electronic device according to claim 3, comprising a supportring between the base and the touch-sensitive input assembly forengaging the piezo disk actuator proximal a perimeter of the piezo diskactuator and wherein said reverse bending of the piezo disk actuatorcomprises bending away from said support ring.
 9. The portableelectronic device according to claim 2, comprising a force sensorbetween the touch-sensitive input assembly and the base for determiningan external applied force on the touch-sensitive input assembly.
 10. Theportable electronic device according to claim 9, wherein the forcesensor is disposed between the piezo disk actuator and the base.
 11. Theportable electronic device according to claim 2 wherein the actuatingarrangement comprises a plurality of piezo disk actuators disposedbetween the touch-sensitive input assembly and the base.
 12. Theportable electronic device according to claim 11, comprising a piezodriver in communication with the processor for controlling applicationof voltage including the applied voltage to apply a force to thetouch-sensitive input assembly and the negative voltage for reversebending of the piezo disk actuators.
 13. The portable electronic deviceaccording to claim 2, wherein the processor is a microprocessor and theportable electronic device comprises a main processor connected to themicroprocessor for communicating therewith.
 14. The portable electronicdevice according to claim 13, wherein the microprocessor is connected tothe touch-sensitive display via the main processor.
 15. The portableelectronic device according to claim 13, wherein the microprocessor isconnected to the accelerometer via the main processor.
 16. A method ofprotecting components of a portable electronic device comprising ahousing including a base, a touch-sensitive input assembly spaced fromand moveable relative to the base, a stopping arrangement to limitmovement of the touch-sensitive input assembly in the direction of thebase, an actuating arrangement comprising a piezoelectric actuatordisposed between the touch-sensitive input assembly and the base toselectively receive an applied voltage to thereby apply a force to thetouch-sensitive input assembly, an accelerometer housed within thehousing, and functional components in the housing comprising a memoryand a processor operably connected to the memory, the touch-sensitiveinput assembly, the piezoelectric actuator, and the accelerometer, themethod comprising: executing a program stored in the memory to monitorsignals from the accelerometer; and if a fall is detected based on thesignals from the accelerometer, apply a negative voltage to thepiezelectric actuator causing reverse bending of the piezoelectricactuator to permit the stopping arrangement to limit movement of thetouch-sensitive input assembly and thereby limit force exerted on thepiezoelectric actuator between the touch-sensitive input assembly andthe base.
 17. A computer-readable medium having computer-readable codeembodied therein, the computer-readable code executable by a processorin a portable electronic device according to claim 1 to cause theportable electronic device to monitor signals from the accelerometer,and if a fall is detected based on the signals from the accelerometer,apply the negative voltage to the piezoelectric actuator causing reversebending of the piezoelectric actuator to permit the stopping arrangementto limit movement of the touch-sensitive input assembly and therebylimit force exerted on the piezoelectric actuator between thetouch-sensitive input assembly and the base.